The primary purpose of the nautical rules of the road, which govern the operation of all boats, is to avoid collision. Good seamanship also dictates that the highest duty of a sailor is to avoid collisions in order to avoid loss of life, personal injury and property damage.
The rules of the road specify the use of navigation lights which are required on all boats. Running lights, which are those navigation lights which are shown while underway, are displayed at night so that a distant boat can observe not only the presence of the first boat but its approximate relative heading.
All boats are required to display at least one red and one green running light, the red being visible through an arc from ahead to 10 points off the port bow and the green being visible through an arc from ahead to 10 points off the starboard bow as illustrated in FIG. 1. Power boats must also display either a stern 12 point white light showing aft and a forward white light of 20 points showing forward or alternatively a 32 point white stern light visible around the horizon. In addition to the red and green lights, a boat under sail need only show the 12 point white stern light showing aft.
Knowledge of these lights permits a skipper of one vessel to determine the approximate relative heading of an observed vessel. Unfortunately it is difficult, especially for pleasure boat skippers who are not full time marine pilots, to quickly make a mental determination of relative heading from observation of the lights. It becomes especially difficult at night if the observed boat is approaching at a rapid rate of speed so that any necessary course changes must be made quickly and the skipper is therefore under pressure. Panic is a real possibility especially for a novice skipper. This problem is often further aggravated by the tired condition of a skipper attempting to reach a port after a long day on the water.
Although a great variety of navigation and safety equipment is well known for use on marine and air vehicles, none is known for use in determining or verifying whether an observed boat is on a potential collision course with an operator's boat.
There is therefore the need for a device which a skipper can use to quickly determine whether the observed boat is on a course which could potentially cause collision with his boat.
There is further a need for a device which will permit a skipper to verify his own judgment of the relative heading of the observed boat and which will alert him to the existence of a dangerous collision condition.